Category Archives: Programming languages

Euro S&P

I am at the IEEE Euro Security and Privacy Conference in London.

The keynote talk was by Sunny Consolvo, who runs Google’s security and privacy UX team, and her topic was user-facing threats to privacy and security. Her first theme was browser warnings, which try to stop users doing what they want to; it’s an interruption, it’s technical and there’s no obvious way forward other than clicking through the warning. In 2013 their SSL warning had a clickthrough rate of 68% while their more explicit and graphic malware warning had only 23% clickthrough. Mozilla’s SSL warning had a much lower 33%, with an icon of a policeman and more explicit tests. After four years of experimenting with watching eyes, corporate styling / branding and extra steps – none of which worked very well – they tried a strategy of clear instruction, attractive preferred choice, and unattractive alternative. The text had less jargon, a low reading level, brevity, specifics, an illustration and colour. Her CHI15 paper shows that the new design did much better, from 69% CTR to 41%. It turns out that many factors are at play; a strong signal is site quality, but this leads many people to continue anyway to sites they have come to trust. The malware clickthrough rate is now down to 5%, and SSL to 21%. That cost five years of a huge team effort, with back-end stuff too as well as UX. It involved huge internal fights, such as with a product manager who wanted the warning to say “this site contains malware” rather than “the site you’re trying to get to contains malware” as it was shorter. Her recent papers are here, here, and here.

A second thread of work is a longitudonal survey of public opinion on privacy ranging from government surveillance to cyber-bullying. This has run since 2015 in sixteen countries. 84% of respondents thought limiting access to online but not public data is very or extremely important. 84% were concerned about hackers vs 55% worried about governments and 53% companies. 20% of Germans are very angry about government access to personal data versus 10% of Brits. Most people believe national security justifies data access (except in South Korea) while no country’s people believes the government should have access to police non-violent crime. Most people everywhere support targeted monitoring but nowhere is there majority support for bulk surveillance. In Germany 53% believed everyone should have the right to send anonymous encrypted email while in the UK it’s 39%. Germans were pessimistic about technology with only 4% believing it was possible to be completely anonymous online. Over 88% believe that freedom of expression is very or extremely important and less than 1% unimportant; but over 70% didn’t believe that cyberbullying should be allowed. Opinions are more varied on extremist religious content, with 10.9% agreeing it should be allowed and 21% saying “it depends”.

Her third thread was intimate partner abuse, which has been experienced by 27% of women and 11% of men. There are typically three phases: a physical control phase where the abuser has access to the survivor’s device and may install malware, or even destroy devices; an escape phase which is high-risk as they try to find a new home, a job and so on; and a life-apart phase when they might want to shield location, email address and phone numbers to escape harassment, and may have lifelong concerns. Risks are greater for poorer people who may not be able to just buy a new phone. Sunny gave some case stories of extreme mate guarding and survivors’ strategies such as using a neighbour’s phone or a computer in a library or at work. It takes seven escape attempts on average to get to life apart. After escape, a survivor may have to restrict childrens’ online activities and sever mutual relationships; letting your child post anything can leak the school location and lead to the abuser turning up. She may have to change career as it can be impossible to work as a self-employed professional if she can no longer advertise. The takeaway is that designers should focus on usability during times of high stress and high risk; they should allow users to have multiple accounts; they should design things so that someone reviewing your history should not be able to tell you deleted anything; they should push 2-factor authentication, unusual activity notifications, and incognito mode. They should also think about how a survivor can capture evidence for use in divorce and custody cases while minimising the trauma. Finally she suggests serious research on other abuse survivors of different age groups and in different countries. For more see her paper here.

I will try to liveblog the rest of the talks in followups to this post.

What you get is what you C

We have a new paper on compiler security appearing this morning at EuroS&P.

Up till now, writers of crypto and security software not only have to fight the bad guys. We also have to deal with compiler writers, who every so often dream up some new optimisation routine which spots the padding instructions that we put in to make our crypto algorithms run in constant time, or the tricks that we use to ensure that sensitive data will be zeroised when a function returns. All of a sudden some critical code is optimised away, your code is insecure, and you scramble to figure out how to outwit the compiler once more.

So while you’re fighting the enemy in front, the compiler writer is a subversive fifth column in your rear.

It’s time that our toolsmiths were our allies rather than our enemies. We have therefore worked out what’s needed for a software writer to tell a compiler that a loop really must be executed in constant time, or that a variable really must be set to zero when a function returns. Languages like C have no way of expressing programmer intent, so we do this by means of code annotations.

Doing it properly turns out to be surprisingly tricky, but we now have a working proof of concept in the form of plugins for LLVM. For more details, and links to the code, see the web page of Laurent Simon, the lead author; the talk slides are here. This is the first technical contribution in our research programme on sustainable security.

CHERI: Architectural support for the scalable implementation of the principle of least privilege

[CHERI tablet photo]
FPGA-based CHERI prototype tablet — a 64-bit RISC processor that boots CheriBSD, a CHERI-enhanced version of the FreeBSD operating system.
Only slightly overdue, this post is about our recent IEEE Security and Privacy 2015 paper, CHERI: A Hybrid Capability-System Architecture for Scalable Software Compartmentalization. We’ve previously written about how our CHERI processor blends a conventional RISC ISA and processor pipeline design with a capability-system model to provide fine-grained memory protection within virtual address spaces (ISCA 2014, ASPLOS 2015). In our this new paper, we explore how CHERI’s capability-system features can be used to implement fine-grained and scalable application compartmentalisation: many (many) sandboxes within a single UNIX process — a far more efficient and programmer-friendly target for secure software than current architectures.

Continue reading CHERI: Architectural support for the scalable implementation of the principle of least privilege

Job ad: pre- and post-doctoral posts in processor, operating system, and compiler security

The CTSRD Project is advertising two posts in processor, operating system, and compiler security. The first is a research assistant position, suitable for candidates who may not have a research background, and the second is a post-doctoral research associate position suitable for candidates who have completed (or will shortly complete) a PhD in computer science or a related field.

The CTSRD Project is investigating fundamental improvements to CPU architecture, operating system (OS) design, and programming language structure in support of computer security. The project is a collaboration between the University of Cambridge and SRI International, and part of the DARPA CRASH research programme on clean-slate computer system design.

These positions will be integral parts of an international team of researchers spanning multiple institutions across academia and industry. Successful candidate will provide support for the larger research effort by contributing to low-level hardware and system-software implementation and experimentation. Responsibilities will include extending Bluespec-based CHERI processor designs, modifying operating system kernels and compiler suites, administering test and development systems, as well as performing performance measurements. The position will also support and engage with early adopter communities for our open-source research platform in the UK and abroad.

Candidates should have strong experience with at least one of Bluespec HDL, OS kernel development (FreeBSD preferred), or compiler internals (LLVM preferred); strong experience with the C programming language and use of revision control in large, collaborative projects is essential. Some experience with computer security and formal methods is also recommended.

Further details on the two posts may be found in job ads NR27772 and NR27782. E-mail queries may be sent directly to Dr Robert N. M. Watson.

Both posts are intended to start on 8 July 2013; applications must be received by 9 May 2013.

CFP: Runtime Environments, Systems, Layering and Virtualized Environments (RESoLVE 2013)

This year, we presented two papers at RESoLVE 2012 relating to the structure of operating systems and hardware, one focused on CPU instruction set security features out of our CTSRD project, and another on efficient and reconfigurable communications in data centres out of our MRC2 project.

I’m pleased to announce the Call for Papers for RESoLVE 2013, a workshop (co-located with ASPLOS 2013) that brings together researchers in both the OS and language level virtual machine communities to exchange ideas and experiences, and to discuss how these separate layers can take advantage of each others’ services. This has a particular interest to the security community, who both want to build, and build on, security properties spanning hardware protection (e.g., VMs) and language-level protection.

Runtime Environments, Systems, Layering and Virtualized Environments
(RESoLVE 2013)

ASPLOS 2013 Workshop, Houston, Texas, USA
March 16, 2013


Today’s applications typically target high-level runtime systems and frameworks. At the same time, the operating systems on which they run are themselves increasingly being deployed on top of (hardware) virtual machines. These trends are enabling applications to be written, tested, and deployed more quickly, while simplifying tasks such as checkpointing, providing fault-tolerance, enabling data and computation migration, and making better, more power-efficient use of hardware infrastructure.

However, much current work on virtualization still focuses on running unmodified legacy systems and most higher-level runtime systems ignore the fact that they are deployed in virtual environments. The workshop on Runtime Environments, Systems, Layering, and Virtualized Environments (RESoLVE 2013) aims to brings together researchers in both the OS and language level virtual machine communities to exchange ideas and experiences and to discuss how these separate layers can take advantage of each others’ services.

Continue reading CFP: Runtime Environments, Systems, Layering and Virtualized Environments (RESoLVE 2013)

ACM Queue interview on research into the hardware-software interface

ACM Queue has posted my August 2012 interview on research into the hardware-software interface. We discuss the importance of a whole-stack view in addressing contemporary application security problems, which are often grounded in how we represent and execute software over lower-level substrates. We need to consider CPU design, operating systems, programming languages, applications, and formal methods — which requires building collaborations that span traditional silos in computer science research. I also consider the impact of open source on software security research methodology, and how we might extend those ideas to CPU research. A motivation for this investigation is our experimental CHERI hybrid capability processor, part of the CTSRD Project, a long-term research collaboration between the security, operating systems, and computer architecture groups at the University of Cambridge Computer Laboratory and the systems and formal methods groups SRI International Computer Science Laboratory.

Job ad: post-doctoral researcher in security, operating systems, computer architecture

We are pleased to announce a job opening at the University of Cambridge Computer Laboratory for a post-doctoral researcher working in the areas of security, operating systems, and computer architecture.

Research Associate in compiler-assisted instrumentation of operating system kernels
University of Cambridge – Faculty of Computer Science and Technology
Salary: £27,578-£35,938 pa

The funds for this post are available for up to two years:

We are seeking a Post-doctoral Research Associate to join the CTSRD and MRC2 projects, which are investigating fundamental revisions to CPU architecture, operating system (OS), programming language, and networking structures in support of computer security. The two projects are collaborations between the University of Cambridge and SRI International, and part of the DARPA CRASH and MRC research programmes on clean-slate computer system design.

This position will be an integral part of an international team of researchers spanning multiple institutions across academia and industry. The successful candidate will contribute to low-level aspects of system software: compilers, language run-times, and OS kernels. Responsibilities will include researching the application of novel dynamic instrumentation techniques to C-language operating systems and applications, including adaptation of the FreeBSD kernel and LLVM compiler suite, and evaluation of the resulting system.

Continue reading Job ad: post-doctoral researcher in security, operating systems, computer architecture

Three-paper Thursday: capability systems

This week, my contribution to our three-paper Thursday research reading list series is on capability systems. Capabilities are unforgeable tokens of authority — capability systems are hardware, operating, or programming systems in which access to resources can occur only using capabilities. Capability system research in the 1970s motivated many fundamental insights into practical articulations of the principle of least privilege, separation of mechanism and policy, and the interactions between program representation and security. They also formed the intellectual foundation for a recent renaissance in capability-oriented microkernels (L4, sel4) and programming languages (Joe-E, Caja, ECMAScript 5). Capability systems have a long history at Cambridge, including the CAP Computer, and more recently, our work on Capsicum: practical capabilities for UNIX. I’ve selected three “must read” papers, but there are plenty of other influential pieces that, unfortunately, space doesn’t allow for!
Continue reading Three-paper Thursday: capability systems